The present invention refers to apparatus for feeding a fiber fleece web to a needling zone of a needling machine and, more particularly, to apparatus of the type comprising a pre-compressor with a lower endless moving belt and an upper endless moving pre-compression belt which is arranged above the lower belt and which forms therewith a gap narrowing in a transport direction of a fiber fleece web to be supplied therethrough, and a supply roller pair arranged in front of the needling zone of the needling machine, said supply roller pair consisting of an upper and a lower supply roller, which form a gap between them and which are provided with non-rotating guide fingers, which each bridge over an upper and a lower gusset gap between the supply rollers and a holding-down member or needle plat of the needling machine.
An apparatus of this kind is common in needling installations and is known from U.S. Pat. No. 5,307,546.
The purpose of the pre-compressor of the apparatus is to reduce the thickness of a fiber fleece web of a loose but very thick structure, i.e. an un-needled fleece web supplied by a fleece laying device, to such an extent that it can be guided into the gap between two positively driven supply rollers supplying the fleece web to a needling machine.
The pre-compressor merely compresses the un-needled fleece web. Depending on the resiliency of the fiber material forming the fleece web, the un-needled fleece web recovers when it leaves the gap between the lower belt and the pre-compression belt arranged above the lower belt. This can lead to difficulties when the fleece web enters the needling machine arranged downstream.
It is therefore the object of the invention to provide an apparatus as set forth above, which enables easy feeding of an un-needled fiber fleece web to a needling machine even if the fibers comprised in the fiber fleece web develop high recovery forces due to their resiliency.
This object is solved by an apparatus of the type referred to above which also comprises a compacting means (device) including at least two compacting rollers forming a gap between one another, said compacting means being arranged between the pre-compressor and the supply roller pair, at least one of the rollers of said compacting means being provided at its periphery with toothed all-steel armaments or being formed as a disk roller having a plurality of toothed disks, the fiber fleece web being fed through the rollers of said compacting means.
The invention supplements a known fleece supply arrangement comprising a pre-compressor and supply roller by a compacting means inserted therebetween which does not only compress the fiber fleece but which also partially re-orientates the fibers therein. It presses fibers perpendicularly to their position in the un-needled fleece into the fleece, similar to a needling process. By the frictional forces and by mutual irritation, the fibers pressed into the fleece keep the fleece in compressed state, so that it cannot recover so easily, as the fleece that was compressed without its fiber structure having been changed be re-orientation of the fibers.
Moreover, the invention enables an especially advantageous utilization of the compacting means for a further purpose that will be described further below.
In a fiber fleece or un-needled fleece web the fibers usually have an orientation extending transversely to the longitudinal extension of the web, said orientation being provided to them by a laying process performed by a fleece laying apparatus. Such a preferred direction of the fiber orientation in the needle fleece manufactured therefrom leads to the consequence that the product, e.g., a felt, has different drawing properties in the different drawing directions, i.e. it reacts differently when being drawn depending on the direction. For instance, its strength transversely to the web direction (transverse strength) is greater than its longitudinal strength.
In order to avoid these properties that are generally disadvantageous, the un-needled fleece web is usually only pre-needled in a first needling step, subsequently subjected to a drawing process in the longitudinal direction to re-orientate the fibers transversely to their prevailing direction that extends transversely to the web direction, and is needled another time in a second needling process. This drawing in the longitudinal direction of the pre-needled fleece web at the same time reduces its surface weight.
It is quite natural that the fibers are less movable in a needled fleece web pre-solidified by pre-needling than in a fully un-solidified un-needled fleece web. Thus, arrangements have been proposed in which a drawing equipment is arranged between a fleece laying apparatus and an intake region of a needling machine, in which the un-solidified un-needled fleece web is drawn. It has been proposed to provide such drawing equipment with a plurality of rollers provided with armaments, which is therefore very expensive. Moreover, it requires a lot of space.
According to an embodiment of the invention, the supply rollers upstream of the needling machine are provided with all-steel armaments, i.e. with a toothing at their circumference, and form an active part of a drawing equipment which further includes the above-mentioned compacting means. The fleece is held substantially positively in this compacting means so that in the case of differently adjusted speeds of rotation of the supply rollers and of the rollers of the compacting means arranged upstream thereof, the fleece web is drawn in the area between the rollers of the compacting means and the supply rollers of the needling machine. If the apparatus comprises a plurality of toothed rollers in the compacting means, a plurality of drawing zones can be realized at the rollers by differently adjusting a plurality of speeds of rotation.
At least one compacting roller pair or at least one compacting roller triple (i.e., with three compacting rollers rather than two) or at least one compacting roller with an opposing compression trough member may be arranged in the supply direction upstream the supply rollers. At least one of these rollers is provided with all-steel armaments on its circumference. The teeth of these armaments press into the un-needed fleece web and entrain fibers that they press into the un-needled fleece web so that a compression and at the same time a certain solidification of the un-needled fleece web is obtained, which counteracts a recovery of the un-needled fleece web after leaving the gaps between the rollers or between the roller and compression trough. Thereby, the guide fingers behind the supply rollers are relieved and the friction is reduced. The supply rollers advance the un-needled fleece web in compacted condition to the first needle row of the needling machine. Tensile forces acting on the fleece web in this part of the path, that would increase fleece mass fluctuations, do therefore not occur.
A press-on roller of a comparatively small diameter and a smooth surface may possibly be arranged between the supply rollers and the discharge side roller of a roller triple arranged upstream thereof, said press-on roller pressing the un-needled fleece web onto the discharge side roller of this roller triple and therefore serves for shortening the drawing zone between the roller triple and the supply rollers.
In the last mentioned portion, a so-called gusset roller of a small diameter in the gusset between the discharge side roller of the roller pair or roller triple of the compacting means and the lower supply roller of the needling machine adjoining same can be arranged, which substantially fills this gusset between the rollers. By means of the gusset roller a possible recovery of the fiber fleece web caused by the resiliency of the fibers is additionally counter-acted.
In the fleece feeding system of the invention according to the embodiment explained, the supply rollers have a double function. On the one hand they participate in the drawing of the un-needled fleece web and on the other hand they determine the supply of the un-needled fleece web in the needling machine. The overall arrangement does not only effect a compression of the un-needled fleece web but also a drawing of same and possibly a solidification and therefore has also at least a double function if not even a triple function. Thus, a significant reduction of the apparatus expenditure and the space requirements can be achieved by the invention.
Conventional carding rollers may be used as rollers having armaments. Furthermore, it must be noted that toothed rollers can also be used instead of rollers provided with all-steel armaments, i.e. rollers that consist of a plurality of toothed disks. The teeth may be provided with notches that point towards the free tooth end (i.e., the distal end of the tooth) and favorably entrain the fibers when pressing into the fiber fleece web and press the fibers into the fleece. The tooth disks may have a mutual distance (i.e., may be spaced) so that it is possible to arrange the rollers of a pair in a manner that the disks of one of the rollers are directed towards the gaps between the rollers of the respective opposing roller. The distance between the rollers can thus be minimized.
The invention will now be explained with reference to the drawings.